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251.
为考察低氧条件下不同电子受体对于克雷伯氏菌(Klebsiella sp.ZS1,下称ZS1)降解菲的影响,在8%氧分压下,分别添加20 mmol/L Na2SO4、20 mmol/L NaNO3、10 mmol/L FeCl3为电子受体进行降解菌的培养. 通过分光光度法和平皿计数法分别测定电子受体消耗率和菌体生长量,并采用气-质联用法(GC-MS)测定ρ(菲),对不同电子受体影响下的菌体生长量和ρ(菲)进行单因素方差分析. 结果表明,在低氧环境下ZS1降解菲过程中,SO42-、NO3-、Fe3+的消耗率分别为74.7%、0.2%、4.5%;电子转移速率分别为1 899、0.366 3、7.679 μmol/d. 未接种ZS1时,ρ(菲)只减少了10.1%;接种ZS1后,不添加电子受体和分别添加SO42-、NO3-、Fe3+下菲的降解率分别为68.9%、86.2%、72.9%和68.5%,一级动力学方程求得的降解速率常数分别为0.181、0.360、0.186、0.183 d-1. 添加SO42-组ZS1的生长量是不添加电子受体组的2.5倍,而添加NO3-或Fe3+时与不添加电子受体组基本相等. 研究显示,在低氧条件下,ZS1降解菲过程中可同时利用SO42-和O2为电子受体;添加SO42-作为外源电子受体对ZS1的生长及降解能力有很强的促进作用;而添加NO3-和添加Fe3+对ZS1降解菲和ZS1的生长没有显著影响. 相似文献
252.
以2013年秋季两个航次的葫芦山湾海洋生态环境调查资料为基础,通过水质、沉积物介质(水化要素12种、沉积物要素6种、生态要素4种)的分析数据,运用主成分层次分析法(AHP-PCA)进行初选。经生态环境质量主驱动力分析,确定了生态潜在风险指数权重,底质污染物中的重金属及石油烃要素为生态风险潜评价因子。在此研究的基础上,系统采用Hakanson指数法模型,并结合ArcG IS的空间矢量叠加分析,对筛选出的2类污染物的潜在生态风险进行综合评估,得出了生态风险等级新结论。从环境地球化学保护角度考虑,提出在该海湾长兴岛和西中岛两侧水域,应进一步严格石油、重金属排海的总量控制。 相似文献
253.
饮用水中挥发性卤代烃的顶空气相色谱分析研究 总被引:2,自引:0,他引:2
本文研究并拟订了一种饮用水中五种挥发性卤代烃的顶空气相色谱分析法,方法灵敏准确,操作简便快速,实际水样分析结果满意 相似文献
254.
255.
256.
多环芳烃在渤海海峡柱状沉积物中的分布 总被引:27,自引:0,他引:27
在渤海海峡(S44和T4站位)柱状沉积物中运用气相色谱法定量地检出13种多环芳烃化合物,并对其含量分布及来源进行了分析.多环芳烃浓度总和为60.3ng/g~2076.5ng/g,尚不属严重污染状况,但是苯并芘等强致癌性化合物均有不同程度检出.利用多环芳烃的一些参数(菲/蒽、荧蒽/芘、2~3环化合物总量和4环以上化合物总量等比值及不同分子量的相对浓度)估测了该区的多环芳烃的来源,S44站位的多环芳烃主要来源于化石燃料的不完全燃烧过程;而在T4显示的是石油源和不完全燃烧源的混合特征,这应与研究海区的石油开发或航运等事件有关.同时研究表明多环芳烃在柱样中的分布可提示人文活动强度的影响. 相似文献
257.
A.H. El‐Sebae S.A. Soliman N.S. Ahmed A. Curley 《Journal of environmental science and health. Part. B》2013,48(4):465-474
Abstract Five organophosphorous insecticides: Leptophos, EPN, Cyano‐fenphos, trichloronate and salithion proved to cause irreversible ataxia not only to chicken but also to mice and sheep. TOCP was included as a reference. Cyanofenphos blocked the catecholamine B‐receptor binding activity with 3H‐norepinephrine at a level similar to that of the specific inhibitor propranolol in the mouse heart preparation. In the lamb heart preparation, the B‐receptor was more sensitive to Leptophos, salithion and TOCP than to propranolol. The six compounds and their oxons were screened for their in‐vitro inhibition to monamine oxidase (MAO), acetyl cholinesterase (AChE) and neurotoxic esterase (NTE) in the brain of either mouse, lamb or chicken. It is believed that their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia. 相似文献
258.
Olsman H Hagberg J Kalbin G Julander A van Bavel B Strid A Tysklind M Engwall M 《Environmental science and pollution research international》2006,13(3):161-169
Goal, Scope and Background The use of polybrominated diphenyl ethers (PBDEs) as flame retardants increases the risk for emissions of other brominated
compounds, such as polybrominated dibenzodioxins (PBDDs) and dibenzofurans (PBDFs). The large homology in structure of PBDD/Fs
and mechanism of toxic action, i.e. the capacity to activate the Ah receptor (AhR) pathway, compared to their well-studied
chlorinated analogues, justifies a raised concern to study the environmental levels and fate of these compounds. Decabromodiphenyl
ether (decaBDE) is the most widely used PBDE today. Studies on photolytic debromination of decaBDE in organic solvents have
shown debromination of decaBDE, as well as formation of PBDFs. However, little is known about the transformation mechanisms
and there are only scarce data on photoproducts and PBDE transformation in environmentally relevant matrices. In this study,
mechanism-specific dioxin bioassays were used to study photolytic formation of AhR agonists in toluene solutions of decaBDE.
In addition, the influence of irradiation time and UV-light wavelength on the formation was studied. PBDE congener patterns
and presence of PBDD/Fs were analysed. Further, AhR agonists were analysed in agricultural soils contaminated with PBDEs.
Soils were also exposed to UV-light to study changes in AhR agonist levels.
Methods Toluene solutions of decaBDE were irradiated using three different spectra of UV-light, simulating UV-A (320-400 nm), UV-AB
(280-400 nm), and UV-ABC (250-400 nm). Additionally, decaBDE solutions were exposed to narrow wavelength intervals (10 nm
bandwidth) with the central wavelengths 280, 290, 300, 310, 320, 330, 340, 350, 360 nm. AhR agonists in decaBDE solutions
were analysed with two different bioassays, the chick embryo liver-cell assay for dioxins (Celcad) and the dioxin responsive,
chemically activated luciferase expression assay (DR-Calux). Also, the decaBDE solutions were analysed with LRGC-LRMS to obtain
PBDE congener patterns for breakdown of decaBDE, and with HRGC-HRMS, for presence of PBDD/Fs. Four soils were exposed to UV-AB
light, under both dry and moist conditions. Levels of AhR agonists in soil extract fractions, before and after UV-exposure,
were analysed with the DR-Calux.
Results and Discussion Significant levels of photoproducts able to activate the AhR pathway, up to 31 ng bio-TEQ/ml, were formed in UV-exposed decaBDE
solutions. The transformation yield of decaBDE into AhR agonists was estimated to be at the 0.1%-level, on a molar basis.
The net formation was highly dependent on wavelength, with the sample irradiated at 330 nm showing the highest level of dioxin-like
activity. No activity was detected in controls. PBDE analysis confirmed decaBDE degradation and a clear time-dependent pattern
for debromination of PBDE congeners. AhR agonist effect in the recalcitrant fractions of the soils corresponded to the levels
of chemically derived TEQs, based only on chlorinated dioxin-like compounds in an earlier study. It was concluded that no
significant levels of other AhR agonists, e.g. PBDFs, were accumulated in the soil. UV-light caused changes in AhR-mediated
activity in the more polar and less persistent fractions of the soils, but it is not known which compounds are responsible
for this.
Recommendations and Perspective . The laboratory experiments in this study show that high levels of AhR agonists can be formed as photoproducts of decaBDE
and it is important to elucidate if and under which conditions this might occur in nature. However, soil analysis indicates
that photoproducts of PBDE do not contribute to the accumulated levels of persistent dioxin-like compounds in agricultural
soil. Still, more data is needed to fully estimate the environmental importance of PBDE photolysis and occurrence of its photoproducts
in other environmental compartments. Analysis with dioxin bioassays enabled us to gather information about photoproducts formed
from decaBDE even though the exact identities of these compounds were not known.
Conclusion Bioassays are valuable for studying environmental transformation processes like this, where chemical analysis and subsequent
toxicological evaluation requires available standard compounds and information on toxicological potency. The use of bioassays
allows a rapid evaluation of toxicological relevance. 相似文献
259.
Song Qu Shoubin Fan Gang Wang Wanqing He Kangli Xu Lei Nie Yuncheng Zhao Qingchun Zhu Tingting Li Guohao Li 《环境科学学报(英文版)》2021,33(11):57-65
Improving our understanding of air pollutant emissions from the asphalt industry is critical for the development and implementation of pollution control policies. In this study, the spatial distribution of potential maximum emissions of volatile organic compounds (VOCs) in the complete life cycle of asphalt mixtures, as well as the particulate matter (PM), asphalt fume, nonmethane hydrocarbons (NMHCs), VOCs, and benzoapyrene (BaP) emissions from typical processes (e.g., asphalt and concrete mixing stations, asphalt heating boilers, and asphalt storage tanks) in asphalt mixing plants, were determined in Beijing in 2017. The results indicated that the potential maximum emissions of VOCs in the complete life cycle of asphalt mixtures were 18,001 ton, with a large contribution from the districts of Daxing, Changping, and Tongzhou. The total emissions of PM, asphalt fume, NMHC, VOCs, and BaP from asphalt mixing plants were 3.1, 12.6, 3.1, 23.5, and 1.9 × 10?3 ton, respectively. The emissions of PM from asphalt and concrete mixing stations contributed the most to the total emissions. The asphalt storage tank was the dominant emission source of VOCs, accounting for 96.1% of the total VOCs emissions in asphalt mixing plants, followed by asphalt heating boilers. The districts of Daxing, Changping, and Shunyi were the dominant regions for the emissions of PM, asphalt fume, NMHC, and BaP, while the districts of Shunyi, Tongzhou, and Changping contributed the most emissions of VOCs. 相似文献
260.
通过实验室动态模拟实验,研究了在不同固/液比例、溶出温度、搅拌强度、沉积物的粒度等条件下,近岸海洋沾污沉积物中石油烃类化合物的释放过程。研究结果表明,石油烃类化合物的溶出浓度与参与溶出过程的固/液相比例成正比:当固液相比例为1/8时,可在30min之内确定溶出/吸附过程的动态平衡点。沉积物中石油烃类物质向海水中的释放,在10min之内,可基本达到最大初始浓度;未经处理的新鲜沉积物样品较烘干研磨样品,更利于油类的释放。溶出温度的升高及剧烈的反应条件,有利于沉积物中石油烃类物质向海水中的释放。沉积物的组成颗粒愈细,释放的初始浓度愈高。 相似文献